Let-back mechanism for looms



June 9, 1925.

Patented June 9, 19.25.

UNITED STATES PATENT orrice.

JOSEPH WILKINSON, OF FAIRHAVEN; MASSACHUSETTS, ASSIGNOR- TO CROMPTO'N & KNOWLES LOOM WORKS, F WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

LET-BACK MECHANISM FOR LOOMS.

Application filed June 18, 1923. Serial No. 645,968.

T 0 all whom. it may concern:

Be it known that I, Josnrir VVILKiNsoN, a citizen of the United States, residing at Fair-haven, in the county of Bristol and State of Massachusetts, have invented a new and useful Let-Back Mechanism for Looms, of which the following is a specification.

This invention relates to a let-back mecha nism for looms, by the use of which the IU woven fabric may be let back or loosened a desired number of picks upon breakage of filling.

It is the object of my invention to provide an improved mechanism for such purposes so designed that the holding pawl will be released when free from the ratchet teeth and that the take-up or feed pawl may be easily and positively disengaged from the ratchet wheel.

A preferred form of my invention is shown in the drawings in which- Fig. 1 is a side elevation of certain parts of a loom embodying my improvements;

Figs. 2 and 3 are detail side elevations.

showing certain of the parts in Fig. 1 in different positions; and

Fig. 4 is a plan view of the parts shown in Fig. 2.

Referring to the drawings, I have shown a portion of a loom side 10 on which is mounted a ratchet wheel 11 connected by suitable gearing (not shown) to the usual take-up roll of the loom. A take-up or feed pawl 12 engages the ratchet wheel 11 and is actuated in any convenient manner, as by an eccentric 13 on the loom crank shaft 1 1. A holding pawl 15 is pivoted at 16 on the loom side and normally prevents backward movement of the ratchet wheel 11.

A two-part let-back pawl 17 is mounted on a fixed stud 18 and is provided with an adjustable stop 19 by which its let-back movement is limited. When the take-up and holding pawls are released, the le-t back pawl is forced backward from the position shown in Fig. 2 to the position shown in Fig. 3, in which latter position it engages the stop 19 and prevents further backward rotation of the ratchet wheel 11.

The usual filling fork 20 is mounted on a fork slide 21 which engages a finger 22 mounted on a cross shaft 23. An arm or lever 24 is also secured to the shaft 23 and is provided with a pin or stud 25 projecting laterally under the holding pawl 15. The lever 24- is also provided with a cam plate or surface 26 at its lower end, which may be moved into position for engagement by the end of the take-up pawl 12.

The parts are shown in their normal or regular position in Fig. 1, with the filling fork slide 21 in its rearward position and the lever 2s't'depressed, so that the holding pawl 15 is permitted to operatively engage the ratchet wheel 11 and the cam plate 26 is out of the path of movement of the take-up pawl 12.

The usual filling fork lever 27 is provided for actuating the slide 21 and is moved by a cam 28 on the loom cam shaft 29. Upon breakage of filling, the filling fork 20 connects the lever 27 to the slide 21 and the slide is thereby pushed to the left in Fig. 1, turning the shaft 23 and moving the lever 24 rearward to the position shown in Figs. 2 and 3.

The stud 25 first engages the holding pawl 15 and raises the same from engagement with the ratchet wheel 11. The eccentric 13 is so timed with relation to the cam 28 that the pawl 15 is engaged and raised during the feeding movement of the take-up pawl 12, at which time the holding pawl 15 is free from the teeth of the ratchet wheel 1'1. The rearward movement of the lever 24k and of the cam plate 26 is continued, so that the cam plate thereafter engages the take-up pawl 12 during its return or forward movement. The head of the pawl thereupon slides upward upon the cam plate 26 until it is disengaged from the ratchet whcel as indicated in Fig. 3. after which the ratchet wheel is free tolet back the fabric until it is checked by the let-back pawl 17. A dwell in the cam 28 maintains the cam plate 26 in rearward position durin the disengaging movement of the take-up pawl 12.

Having described the construction and operation of my improved let-back mechanism the advantages thereof will be readily apparent. The holding pawl is raised from the ratchet wheel at a time when it is free from all holding strain and the take-up pawl is disengaged from the ratchet wheel by the cam action of the pawl itself against the cam plate 26, the pawl being positively forced against the cam plate by its eccentric driving mechanism.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed otherwise than as set forth in the claims, but what I claim is 5 I. In a loom, a take-up mechanism comprising a ratchet wheel, a take-up pawl for said ratchet wheel, actuatinp" mechanism therefor,a holding pawl, a let-back pawl, means to disengage said holding pawlfrom said ratchet wheel while said ratchet wheel is being moved by said take-up pawl, and to thereafter disengage said take-up pawl from said ratchet wheel on the idle return movement of said take-up pawl.

2. Ina loom' a take-up mechanism comprising a ratchet wheel, a take-up pawl for said ratchet wheel, a holding pawl, a letback pawl, means to move said take-up pawl, and means to remove said holding pawl from operative position while said take up pawl is advancing said ratchet said ratchet wheel, a holding pawl, a letback pawl, a filling fork slide, a release lever actuated thereby and en 'agin'g said holding pawl during feeding movement of said takeup pawl, and a cam plate on said lever movable with said lever on breakage of filling into position for engagement by said take-up pawl on its idle return movement, thereby causing disengagement of said take-up pawl from said ratchet wheel while said pawl is inoperative.

In testimony whereof I have hereunto aflixed'iny signature.

JOSEPH lVILKINSON 

